linux-toradex.git/drivers/clk/clk.c, branch v3.11

Merge tag 'clk-for-linus-3.11' of git://git.linaro.org/people/mturquette/linux

2013-07-03T18:54:50+00:00

Pull clock framework updates from Mike Turquette:
 "The common clock framework changes for 3.11 include new clock drivers
  across several different platforms and architectures, fixes to
  existing drivers, a MAINTAINERS file fix and improvements to the basic
  clock types that allow them to be of use to more platforms than before.

  Only a few fixes to the core framework are included with most all of
  the changes landing in the various clock drivers themselves."

* tag 'clk-for-linus-3.11' of git://git.linaro.org/people/mturquette/linux: (55 commits)
  clk: tegra: fix ifdef for tegra_periph_reset_assert inline
  clk: tegra: provide tegra_periph_reset_assert alternative
  clk: exynos4: Fix clock aliases for cpufreq related clocks
  clk: samsung: Add MUX_FA macro to pass flag and alias
  clk: add support for Rockchip gate clocks
  clk: vexpress: Make the clock drivers directly available for arm64
  clk: vexpress: Use full node name to identify individual clocks
  clk: tegra: T114: add DFLL DVCO reset control
  clk: tegra: T114: add DFLL source clocks
  clk: tegra: T114: add FCPU clock shaper programming, needed by the DFLL
  clk: gate: add CLK_GATE_HIWORD_MASK
  clk: divider: add CLK_DIVIDER_HIWORD_MASK flag
  clk: mux: add CLK_MUX_HIWORD_MASK
  clk: Always notify whole subtree when reparenting
  MAINTAINERS: make drivers/clk entry match subdirs
  clk: honor CLK_GET_RATE_NOCACHE in clk_set_rate
  clk: use clk_get_rate() for debugfs
  clk: tegra: Use override bits when needed
  clk: tegra: override bits for Tegra30 PLLM
  clk: tegra: override bits for Tegra114 PLLM
  ...

clk: Always notify whole subtree when reparenting

2013-06-15T21:34:41+00:00

A clock's notifier count only reflects notifiers which are registered
directly for that clock. A reparent operation though affects the whole
subtree because of a potential rate change.
When issuing the pre rate change notifications only the notifier count
for the clock to be changed is considered and notifiers for subclocks
may never be called. Resulting in clocks in the subtree which have
registered notifiers, may receive a POST_- or ABORT_RATE_CHANGE
notification, without a PRE_RATE_CHANGE_NOTIFICATION.
Therefore always traverse the whole subtree when issueing pre rate
change notifications during a reparent operation.

Signed-off-by: Soren Brinkmann 
Signed-off-by: Mike Turquette

clk: honor CLK_GET_RATE_NOCACHE in clk_set_rate

2013-06-12T01:04:08+00:00

clk_set_rate() uses clk->rate directly. This causes problems if the clock
is marked as CLK_GET_RATE_NOCACHE. Hence call clk_get_rate() to get the
current rate.

Signed-off-by: Peter De Schrijver 
Signed-off-by: Mike Turquette

clk: use clk_get_rate() for debugfs

2013-06-12T01:03:54+00:00

debugfs uses the rate field directly. However this ignores the
CLK_GET_RATE_NOCACHE flag. Call clk_get_rate() instead.

Tested-by: Mark Zhang 
Signed-off-by: Peter De Schrijver 
Signed-off-by: Mike Turquette

clk: remove notifier from list before freeing it

2013-06-07T01:22:52+00:00

The @cn is stay in @clk_notifier_list after it is freed, it cause
memory corruption.

Example, if @clk is registered(first), unregistered(first),
registered(second), unregistered(second).

The freed @cn will be used when @clk is registered(second),
and the bug will be happened when @clk is unregistered(second):

[  517.040000] clk_notif_dbg clk_notif_dbg.1: clk_notifier_unregister()
[  517.040000] Unable to handle kernel paging request at virtual address 00df3008
[  517.050000] pgd = ed858000
[  517.050000] [00df3008] *pgd=00000000
[  517.060000] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[  517.060000] Modules linked in: clk_notif_dbg(O-) [last unloaded: clk_notif_dbg]
[  517.060000] CPU: 1 PID: 499 Comm: modprobe Tainted: G           O 3.10.0-rc3-00119-ga93cb29-dirty #85
[  517.060000] task: ee1e0180 ti: ee3e6000 task.ti: ee3e6000
[  517.060000] PC is at srcu_readers_seq_idx+0x48/0x84
[  517.060000] LR is at srcu_readers_seq_idx+0x60/0x84
[  517.060000] pc : []    lr : []    psr: 80070013
[  517.060000] sp : ee3e7d48  ip : 00000000  fp : ee3e7d6c
[  517.060000] r10: 00000000  r9 : ee3e6000  r8 : 00000000
[  517.060000] r7 : ed84fe4c  r6 : c068ec90  r5 : c068e430  r4 : 00000000
[  517.060000] r3 : 00df3000  r2 : 00000000  r1 : 00000002  r0 : 00000000
[  517.060000] Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[  517.060000] Control: 18c5387d  Table: 2d85804a  DAC: 00000015
[  517.060000] Process modprobe (pid: 499, stack limit = 0xee3e6238)
[  517.060000] Stack: (0xee3e7d48 to 0xee3e8000)
....
[  517.060000] [] (srcu_readers_seq_idx+0x48/0x84) from [] (try_check_zero+0x34/0xfc)
[  517.060000] [] (try_check_zero+0x34/0xfc) from [] (srcu_advance_batches+0x58/0x114)
[  517.060000] [] (srcu_advance_batches+0x58/0x114) from [] (__synchronize_srcu+0x114/0x1ac)
[  517.060000] [] (__synchronize_srcu+0x114/0x1ac) from [] (synchronize_srcu+0x2c/0x34)
[  517.060000] [] (synchronize_srcu+0x2c/0x34) from [] (srcu_notifier_chain_unregister+0x68/0x74)
[  517.060000] [] (srcu_notifier_chain_unregister+0x68/0x74) from [] (clk_notifier_unregister+0x7c/0xc0)
[  517.060000] [] (clk_notifier_unregister+0x7c/0xc0) from [] (clk_notif_dbg_remove+0x34/0x9c [clk_notif_dbg])
[  517.060000] [] (clk_notif_dbg_remove+0x34/0x9c [clk_notif_dbg]) from [] (platform_drv_remove+0x24/0x28)
[  517.060000] [] (platform_drv_remove+0x24/0x28) from [] (__device_release_driver+0x8c/0xd4)
[  517.060000] [] (__device_release_driver+0x8c/0xd4) from [] (driver_detach+0x9c/0xc4)
[  517.060000] [] (driver_detach+0x9c/0xc4) from [] (bus_remove_driver+0xcc/0xfc)
[  517.060000] [] (bus_remove_driver+0xcc/0xfc) from [] (driver_unregister+0x54/0x78)
[  517.060000] [] (driver_unregister+0x54/0x78) from [] (platform_driver_unregister+0x1c/0x20)
[  517.060000] [] (platform_driver_unregister+0x1c/0x20) from [] (clk_notif_dbg_driver_exit+0x14/0x1c [clk_notif_dbg])
[  517.060000] [] (clk_notif_dbg_driver_exit+0x14/0x1c [clk_notif_dbg]) from [] (SyS_delete_module+0x200/0x28c)
[  517.060000] [] (SyS_delete_module+0x200/0x28c) from [] (ret_fast_syscall+0x0/0x48)
[  517.060000] Code: e5973004 e7911102 e0833001 e2881002 (e7933101)

Cc: stable@kernel.org
Reported-by: Sören Brinkmann 
Signed-off-by: Lai Jiangshan 
Tested-by: Sören Brinkmann 
Signed-off-by: Mike Turquette 
[mturquette@linaro.org: shortened $SUBJECT]

clk: Disable unused clocks after deferred probing is done

2013-05-29T07:52:20+00:00

With deferred probing, late_initcall() is too soon to declare a clock as
unused. Wait for deferred probing to finish before declaring a clock as
unused. Since deferred probing is done in late_initcall(), do the unused
check to late_initcall_sync.

Signed-off-by: Saravana Kannan 
Signed-off-by: Mike Turquette

clk: Fix race condition between clk_set_parent and clk_enable()

2013-05-29T05:50:32+00:00

Without this patch, the following race condition is possible.
* clk-A has two parents - clk-X and clk-Y.
* All three are disabled and clk-X is current parent.
* Thread A: clk_set_parent(clk-A, clk-Y).
* Thread A: 
* Thread A: Grabs enable lock.
* Thread A: Sees enable count of clk-A is 0, so doesn't enable clk-Y.
* Thread A: Updates clk-A SW parent to clk-Y
* Thread A: Releases enable lock.
* Thread B: clk_enable(clk-A).
* Thread B: clk_enable() enables clk-Y, then enabled clk-A and returns.

clk-A is now enabled in software, but not clocking in hardware since the
hardware parent is still clk-X.

The only way to avoid race conditions between clk_set_parent() and
clk_enable/disable() is to ensure that clk_enable/disable() calls don't
require changes to hardware enable state between changes to software clock
topology and hardware clock topology.

The options to achieve the above are:
1. Grab the enable lock before changing software/hardware topology and
   release it afterwards.
2. Keep the clock enabled for the duration of software/hardware topology
   change so that any additional enable/disable calls don't try to change
   the hardware state. Once the topology change is complete, the clock can
   be put back in its original enable state.

Option (1) is not an acceptable solution since the set_parent() ops might
need to sleep.

Therefore, this patch implements option (2).

This patch doesn't violate any API semantics. clk_disable() doesn't
guarantee that the clock is actually disabled. So, no clients of a clock
can assume that a clock is disabled after their last call to clk_disable().
So, enabling the clock during a parent change is not a violation of any API
semantics.

This also has the nice side effect of simplifying the error handling code.

Signed-off-by: Saravana Kannan 
Acked-by: Ulf Hansson 
Signed-off-by: Mike Turquette 
[mturquette@linaro.org: fixed up whitespace issue]

clk: add clk_ignore_unused option to keep boot clocks on

2013-04-28T06:03:43+00:00

This is primarily useful when there's a driver that doesn't claim clocks
properly, but the bootloader leaves them on. It's not expected to be used
in normal cases, but for bringup and debug it's very useful to have the
option to not gate unclaimed clocks that are still on.

Signed-off-by: Olof Johansson 
Signed-off-by: Mike Turquette 
[mturquette@linaro.org: fixed up trivial merge issue]

clk: export __clk_get_flags for modular clock providers

2013-04-15T21:50:17+00:00

The common clock api provides some helpers for clk-providers but does
not export these helpers. This hinders clk-providers to be built as modules.
This patch adds __clk_get_flags() to the list of exported symbols.

Signed-off-by: Sebastian Hesselbarth 
Signed-off-by: Mike Turquette

clk: Properly handle notifier return values

2013-04-10T23:33:53+00:00

Notifiers may return NOTIFY_(OK|DONE|STOP|BAD). The CCF uses an
inconsistent mix of checking against NOTIFY_STOP or NOTIFY_BAD.
This inconsistency leaves errors undetected in some cases:
clk_set_parent() calls __clk_speculate_rates(), which stops when it
hits a NOTIFIER_BAD (STOP is ignored), and passes this value back to the
caller.
clk_set_parent() compares this return value against NOTIFY_STOP only,
ignoring NOTIFY_BAD returns.

Use NOTIFY_STOP_MASK to detect a negative notifier return value and
document all four return value options.

Signed-off-by: Soren Brinkmann 
Signed-off-by: Mike Turquette